Empire of Nicaea

The Empire of Nicaea was a Byzantine rump state which existed from 1204 to 1261 following the fall of Constantinople during the Fourth Crusade. Based from the city of Nicaea in Asia Minor, where the Laskaris family established its base of power, the Empire of Nicaea claimed the legacy of the Roman Empire and fought against the crusaders' Latin Empire in the west and the Seljuk Sultanate of Rum in the east. Theodore I Laskaris, who reigned from 1204 to 1222, allied with the Second Bulgarian Empire to fight off the Latins, while he personally slew the Seljuk sultan Kaykhusraw I at the Battle of Antioch on the Meander. In 1222, upon Theodore's death, his son-in-law John III Ducas Vatatzes became the new Emperor, and, at the 1224 Battle of Poimaneon, he defeated the rival Laskaris princes and their Latin allies and regained almost all of the Asian territories held by the Latin Empire in the process. In 1235, John - with the help of Bulgaria - extended his influence over Thessalonica and Epirus in mainland Europe, and the Mongol invasion of Seljuk lands in 1242 prevented the Turks from threatening the Nicenes to the east. In 1246, John attacked Bulgaria and recovered most of Thrace and Macedonia, and he continued to take lands from the Latins until 1254. His son Theodore II Lascaris defended Thrace from the Bulgarians and also warred with the Despotate of Epirus, and, in 1259, Michael VIII Palaeologus defeated the armies of the Kingdom of Sicily, the Despotate of Epirus, and the Latin Empire in the Battle of Pelagonia. From 1260 to 1261, Michael besieged Constantinople, burning the Venetian quarter upon the city's fall. He was recognized as emperor a few weeks later, restoring the Byzantine Empire under the Palaeologus dynasty. The Principality of Achaea was recaptured shortly after, but the Empire of Trebizond and Epirus remained independent Byzantine states.